Global average surface temperature has increased by 0.6°C during the twentieth century, providing clear evidence that climate change is occurring. It is likely that an increase in air temperature will result in a corresponding increase in the water temperature of rivers and lakes. However, there is an overall lack of good quality, long-term water temperature monitoring data with which to investigate such warming trends. This project aims to identify the available water temperature datasets in England and Wales, and to compile a database containing all ongoing water temperature monitoring. Statistical analysis of the database has been undertaken in order to identify any recent annual or seasonal warming trends that might be attributed to climate change. It was agreed by the project board that two examples of each Water Framework Directive (WFD) river type should be selected in each region in addition to one large river which had multiple sampling sites covering a range of WFD types between its upper and lower reaches.